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HalAir Projects Log / Diary

@HaldorLonningdal. Excellent job

Side-tracked with a present-making for Christmas:

Used a 60deg V-bit single pass 3mm deep and 5% stepover.
Feed rate 2500mm/min at 9K rpm (Not Xcarve) so the full carve took approx 30minutes. The board is 280x450mm bamboo.

Laid the epoxy on thick and ended up skim-cutting the board once cured vs sanding the excess off.
3000mm/min and 0.5mm depth per pass using a 20mm flat bit, no apparent heat build-up :slight_smile:

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My soaring club is hosting a contest this weekend so I just had to make a few plaques :slight_smile:
IKEA APTITLIG cutter board, one board allow for 4 plaques.

Simple V-bit engraving with coloured epoxy, sanded down. As these are not intended to be used with food I shot several layers of clear coat on top.

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They look awesome

Thank you Philip :). Its been a while since I carved much but the occasion called for it :slight_smile:

Here is a quick video of it while tidying up the image design:
https://discuss-assets.s3.amazonaws.com/original/3X/e/6/e63c48ddea5e51a4ea79330afeeabe9901dff53b.mp4

Have you thought of using drill bits to create the holes? A CNC makes a handy automated drill press.

Yes, but I dont have a collett system that take the wide range of drill bit diameters I use. So I cheat using CNC-bits.
At the moment I have 3/4/6mm collett on hand and most of my hole making is less than 3mm which in some cases get tapped to M3. So I “hole” to 2.4mm and tap them.

I do want at a later stage have the CNC do the threading aswell, but havent spent the cash on a threading mill yet as they are fairly pricey :slight_smile:

Another project - this will be the largest thing I have machined to date :slight_smile:

History:
I have in the past made a set of stereo speakers (Fullrange Line Array with 20x 3,5" driver per side, 6’6" tall) using hand tools. I am now in the process of upgrading them and while I am at is utilize my CNC :slight_smile:
My current set sound stellar but I can do better :wink:

Preview rendering:

Fusion360-file with test baffle (will make a test cabinet to measure internal volume vs stuffing vs impedance)

Physical parts made to check fit, these parts will also form the test cabinet.
LA-Test

CAM-files for the front baffle, it will be made as one long single piece => tile carving.
Three different carve programs will be run, one for the top4 speakers, one for the mid-4 speakers and lastly one for the bottom-4 speakers. Total baffle length = 2076mm, carved from 19mm MDF.
Total carve time per complete baffle approx 3hrs.

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While waiting for winter I have CNC’d a test cabinet.
The test cabinet will serve two purposes, 1) test EpoxyGranite (EG) casting process / construction and 2) experiment with stuffing etc to diffuse internal reflections.

Tip - EG is a very good medium for CNC’s in general…

Hope to start machining the front baffles later this month as the next couple of weeks are rather buzy :wink:

Test cabinet done:

PVC piping conformed to proper shape, acting as an internal cast barrier. Its extracted after curing of the EG:

Mixing the EG up:

Just a quick video from my machining test before committing to the long one-piece front baffle :slight_smile:
The end mill used is a 6mm ball mill with a long shank.

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After a couple of weeks with a lot of travel I am back at it. Redesigned my speaker array front baffle and last night prepared the gcode files.
It will be my largest carve to date, spanning 2100mm in length and represent about 3hrs of carve time per baffle. The total length of the carve is divided into 6 sub-carves, each using two tools for the job. 6mm flat endmill for roughing, contour cuts etc (10min) and a 6mm ballnose for curvature (20mins)

If I am lucky (:crossed_fingers:) I might get to do the first carve during this weekend. Due to size of material and length of carve I need to temporarely move my CNC to either outside in the garden or into the garage :scream:

Fusion360 CAM simulation:

Baffle render preview:

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On Sunday I wanted to do a fullscale prototype test of one baffle, end result was a blown Makita. It has served me well for like 4yrs now with zero issues, but this time the RPM /softstart governor blew.

Due to either a mechanical og software glitch the bit didnt retract as it was supposed to before plunging and went “double down” causing the collett nut to hit material and all axes stalled out when it attempted to move.
This made the RPM governor to blow (pop and smoke) depsite I was only 2s away from the “Ohhh_sh****t”-button.

When the governor blows the Makita go to max RPM only so beware

Carve was ruined, no RPM control and I’ve sent the Makita off for repair :frowning:

The Makita is tough but this accident would be a bit too much for any spindle. Did you damage your X/Z axis at the same time? I had a serious crash with my Shapeoko a while back, the bit descended about and inch through a piece of Maple and into my wasteboard before I could stop it. The Makita was not damaged but it damaged the set screws of the Z stepper gear and also had to readjust and re-tram the Z.

Absolutely.
If I had used a VDF spindle I could have set an upper current limit where it would shut down (the spindle atleast)
Perhaps a fast-acting fuse might have helped…

My machine is not an Xcarve, using ACME-screws on Y and 1605-screws for X and Z so can provide quite a bit of radial pull.
I have carved MDF with a 6mm 1F bit at 2500mm/min at 12mm DoC before and it didnt skip a beeat.
The cutter length of my bit (25mm) was less than the material (2x18mm MDF) so I guess it overloaded when the machine wanted to move sideways and the shank held it back.

I absolutely need to go over my machine after a crash like this, scheduled for this weekend :slight_smile:

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Operational again :crossed_fingers: :grinning:

Yesterday I started a new baffle, hopefully it will come out good but I am anxious due to the mishaps which very quickly can ruin hours of work

Only had time to do the top 4 driver positions (1 carve with 3 tool operations)
On the machine bed I have attached a gude plate (second surface with rails) that ensure the MDF-stock stay parallell to the Y-axis of the machine.

Pilot and guide holes ensure I can do partial segments with equal spacing, simply lifting the stock-MDF up, slide to the right and align it with the guide hole. Clamp down and machine next segment. Like mentioned before one baffle consist of 6 segments, one top, 4 repeats of middle and one bottom.

1 down, 5 to go…!
(and repeat for 2nd baffle…if all goes well)

  • First operation, doing the pilot and guide hole with 6mm flat tool. CC spacing is 4x84mm (20s)
  • Second operation, machining the driver openings and mounting flange with 6mm flat tool (10min)
  • Third operation, contouring the waveguide surface with 6mm ball tool (20min)

I could do finer contouring but that = more machine time. Earlier tests show that the visible contouring lines quickly dissapear with light sanding in preparation of finishing. I will seal the MDF with epoxy resin which will serve as the primer/base coat.



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The contour carving of both baffles came out great and have been primed with 2 coats of epoxy. They will later be prepped for paint but for the time being they are as seen here :slight_smile:
Some glue residue on the corners are showing but will be removed when I prep them for paint.

To date my largest CNC project :slight_smile:
(210cm tall)

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